The reactivity of yellow arsenic and the interpnictogen compound AsP3 towards low-valent group 13 compounds was investigated. The reactions of [LAl] (1, L=[{N(C6H3iPr2-2,6)C(Me)}2CH]−) with As4 and AsP3 lead to [(LAl)2(μ,η1:1:1:1-E4)] (E4=As4 (3 b), AsP3 (3 c)) by insertion of two fragments [LAl] into two of the six E−E edges of the E4 tetrahedra. Furthermore, the reaction of [LGa] (2) with E4 afforded [LGa(η1:1-E4)] (E4=As4 (4 b), AsP3 (4 c)). In these compounds, only one E−E bond of the E4 tetrahedra was cleaved. These compounds represent the first examples of the conversion of yellow arsenic and AsP3, respectively, with group 13 compounds. Furthermore, the reactivity of the gallium complexes towards unsaturated transition metal units or polypnictogen (En) ligand complexes was investigated. This leads to the heterobimetallic compounds [(LGa)(μ,η2:1:1-P4)(LNi)] (5 a), [(Cp’’’Co)(μ,η4:1:1-E4)(LGa)] (E=P (6 a), As (6 b), Cp’’’=η5-C5H2tBu3) and [(Cp’’’Ni)(η3:1:1-E3)(LGa)] (E=P (7 a), As (7 b)), which combine two different ligand systems in one complex (nacnac and Cp) as well as two different types of metals (main group and transition metals). The products were characterized by crystallographic and spectroscopic methods.